To solve the equation 8x + 9x = -19, we can combine like terms on the left side of the equation:

8x + 9x = 17x

So the equation becomes:

17x = -19

To isolate x, we divide both sides of the equation by 17:

(17x)/17 = (-19)/17

x = -19/17

Therefore, the solution to the equation is x = -19/17.